A reflective electrochromic device (ECD) based on polymeric microspheres was proposed, and its feasibility for a display was investigated. The viologen moiety was introduced onto the surface of chloro-functionalized polymeric microspheres via refluxing in toluene. The existence of the viologen pendants was confirmed with X-ray photoelectron spectroscopy, and their redox reactions were examined with cyclic voltammetry. The ECD had an inherent white background without an applied potential because the micrometer size range of the substrate particles scattered the light, whereas a deep violet color appeared when 3.0 V was applied to the cell. This color change could have been caused by the reduction of viologen pendants on the surface of the polymeric microspheres. The reflectance values of the ECD were observed with a spectrophotometer, and the response times and cyclic stability of the ECD, depending on the potential, were also examined. (c) 2005 Wiley Periodicals, Inc.